When to Plant Onions in Maryland
In Maryland, the time to plant onions outside runs from Feb 24 – Mar 10 in Baltimore to Apr 1 – Apr 15 in Frostburg. In Baltimore, it's Feb 24 – Mar 10. The average last spring frost differs by about 5 weeks across the state (Mar 24 in Baltimore, Apr 29 in Frostburg), so use the dates for the town nearest you.
Onions are cold-hardy. Plant sets or transplants early so they grow leaves before long summer days trigger bulbing.
- Start indoors: 10–12 weeks before the last frost.
- Plant outside: 2–4 weeks before the last frost.
Onions planting dates in Maryland by city
| City | Zone | Start indoors | Plant outside |
|---|---|---|---|
| Aberdeen | 7b | Jan 16 – Jan 30 | Mar 13 – Mar 27 |
| Annapolis | 8a | Jan 2 – Jan 16 | Feb 27 – Mar 13 |
| Baltimore | 8a | Dec 30 – Jan 13 | Feb 24 – Mar 10 |
| Bel Air | 7b | Jan 16 – Jan 30 | Mar 13 – Mar 27 |
| Bladensburg | 7b | Jan 4 – Jan 18 | Mar 1 – Mar 15 |
| Bowie | 7a | Jan 28 – Feb 11 | Mar 25 – Apr 8 |
| Brunswick | 7a | Feb 1 – Feb 15 | Mar 29 – Apr 12 |
| Cambridge | 8a | Jan 7 – Jan 21 | Mar 4 – Mar 18 |
| Chesapeake Beach | 8a | Jan 15 – Jan 29 | Mar 12 – Mar 26 |
| Cheverly | 7b | Jan 4 – Jan 18 | Mar 1 – Mar 15 |
| College Park | 7b | Jan 16 – Jan 30 | Mar 13 – Mar 27 |
| Cumberland | 7a | Jan 21 – Feb 4 | Mar 18 – Apr 1 |
| District Heights | 7b | Jan 4 – Jan 18 | Mar 1 – Mar 15 |
| Easton | 8a | Jan 7 – Jan 21 | Mar 4 – Mar 18 |
| Elkton | 7b | Jan 13 – Jan 27 | Mar 10 – Mar 24 |
| Frederick | 7b | Jan 8 – Jan 22 | Mar 5 – Mar 19 |
| Frostburg | 6b | Feb 4 – Feb 18 | Apr 1 – Apr 15 |
| Fruitland | 7b | Jan 9 – Jan 23 | Mar 6 – Mar 20 |
| Gaithersburg | 7b | Jan 7 – Jan 21 | Mar 4 – Mar 18 |
| Glenarden | 7b | Jan 28 – Feb 11 | Mar 25 – Apr 8 |
| Greenbelt | 7b | Jan 16 – Jan 30 | Mar 13 – Mar 27 |
| Hagerstown | 7a | Jan 17 – Jan 31 | Mar 14 – Mar 28 |
| Hampstead | 7a | Jan 25 – Feb 8 | Mar 22 – Apr 5 |
| Havre de Grace | 7b | Jan 16 – Jan 30 | Mar 13 – Mar 27 |
| Hyattsville | 7b | Jan 4 – Jan 18 | Mar 1 – Mar 15 |
| La Plata | 7b | Jan 23 – Feb 6 | Mar 20 – Apr 3 |
| Laurel | 7b | Jan 11 – Jan 25 | Mar 8 – Mar 22 |
| Mount Airy | 7a | Jan 20 – Feb 3 | Mar 17 – Mar 31 |
| Mount Rainier | 7b | Jan 4 – Jan 18 | Mar 1 – Mar 15 |
| New Carrollton | 7b | Jan 28 – Feb 11 | Mar 25 – Apr 8 |
| Ocean City | 8a | Jan 13 – Jan 27 | Mar 10 – Mar 24 |
| Poolesville | 7b | Jan 19 – Feb 2 | Mar 16 – Mar 30 |
| Riverdale Park | 7b | Jan 4 – Jan 18 | Mar 1 – Mar 15 |
| Rockville | 7b | Jan 7 – Jan 21 | Mar 4 – Mar 18 |
| Salisbury | 7b | Jan 9 – Jan 23 | Mar 6 – Mar 20 |
| Takoma Park | 7b | Jan 4 – Jan 18 | Mar 1 – Mar 15 |
| Taneytown | 7a | Jan 28 – Feb 11 | Mar 25 – Apr 8 |
| Thurmont | 7a | Jan 20 – Feb 3 | Mar 17 – Mar 31 |
| Walkersville | 7a | Jan 8 – Jan 22 | Mar 5 – Mar 19 |
| Westminster | 7a | Jan 30 – Feb 13 | Mar 27 – Apr 10 |
Calculated from each town's average (50%) frost dates, from the nearest NOAA station (1991–2020). Typical dates for the 2027 planting season, based on NOAA's 1991–2020 averages. They are long-term odds, not a forecast: always check your local forecast before planting. Zones: 2023 USDA Plant Hardiness Zone Map (USDA-ARS and Oregon State University). Not the official map; see planthardiness.ars.usda.gov.
See all frost dates in Maryland, or the general guide to when to plant onions.
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